Creating a character sheet takes a good working knowledge of the game system, coding skills, and a pro account. It's possible there's a fan out there with those qualifications who would be interested in helping you out but I wouldn't hold my breath. Star Trek CODA is pretty old and obscure these days. The Modiphius 2d20 Star Trek Adventures sheet works well if you're okay with changing systems. I don't know if there's another 2d6 system sheet on Roll20 that you could finagle into working. And it's always possible to create a generic sheet to hold a player's stats and roll the dice manually with either the /roll command or the dice toolbar.